USGS Scientific Investigations Report 2013–5001  - Sources and Characteristics of Organic Matter in the Clackamas River, Oregon, Related to the Formation of Disinfection By-Products in Treated Drinking Water 

Table 8. Trends in source-water and finished-water quality during two storms in the Clackamas River basin, Oregon, October–November 2010 at the Clackamas River Water drinking-water treatment plant. 

[For ease in comparision among sampling dates, red and black arrows indicate trends in constituent values. Abbreviations: mg/L, milligram per liter; µg/L, microgram per liter; nm, nanometers] 

Parameter	Pre-storm (October 5, 2010)	Trend	“Initial” autumn storm event  (October 10, 2010)	Trend	“Major flush” event  (November 1, 2010)
Clackamas River Water—source water
Streamflow, in cubic feet per second	951	↑	1,548	↑	2,247
Turbidity, in nephelometric units	0.5	↑	4.5	↓	2.1
Dissolved organic carbon, in mg/L	1.3	↑	1.6	↑	2.0
Total particulate carbon, in mg/L	0.41	↑	0.98	↓	0.23
Total particulate nitrogen, in mg/L	0.06	↑	0.11	↓	0.04
Chlorophyll-a (water column), in µg/L	1.7	↑	3.8	↓	2.3
Specific ultraviolet absorbance at 254 liters per milligram per meter	2.08	↑	2.75	↑	3.25
Fluorescence index	1.41	↑	1.44	↓	1.40
Humic index	3.52	↑	3.61	↑	4.29
Percentage of component C1	19	↑	29	↓	18
Percentage of component C2	13	↓	12	↑	18
Percentage of component C3	24	↓	21	↑	28
Percentage of component C4	22	↓	20	↑	24
Percentage of component C5	22	↓	17	↓	12
Clackamas River Water—finished water
Total trihalomethanes (THM4)	0.033	↓	0.025	↑	0.026
Total haloacetic acids (HAA5)	0.026	↓	0.020	↑	0.029